Adult strawberry sap beetles, Stelidota geminata, are less than
1/8 inch long, oval-shaped, and mottled brown in color. They fly into
strawberry plantings from wooded areas at about the time berries begin
to ripen; they are particularly attracted to over-ripe berries.
Their feeding leaves deep cavities in berries, and females then deposit
eggs on the injured fruit. Although larvae feed in berries, they usually
are unnoticed because the fruit has already begun to decompose as a result
of damage caused by adults. Because over-ripe fruit is especially attractive
to sap beetles, damage is often greatest in U-Pick operations where pickers
leave large numbers of ripe and over-ripe berries in the field.
Strawberry sap beetles are best controlled by timely and complete ("clean")
picking and the removal of over-ripe and damaged berries. Because sap
beetle populations usually do not build up until the picking cycle is
underway, the use of insecticides is limited by frequent harvests. Certain
insecticides are effective against sap beetles but can be used in strawberries
only if the preharvest interval of 3-5 days is obeyed. Placing "trap
buckets" of over-ripe fruit outside field borders can intercept immigrating
beetles and reduce numbers in the crop.